Coated wrapping paper



Patented Oct. 20, 1936 2,oss,oz1 I PATENT OFFICE 2,058,021 COATED WRAPPING. PAPER Edouard M. Kratz, Gary, Ind., assignor, by memo assignments, to Marbo Products Corporation, Chicago, 111., a corporation of Delaware No Drawing.

Application March 22, 1934,

Serial No. 716,909 3 Claims. ,(01. 91-68) This invention relates to a wrapping paper coated withgelatine, casein, or other protein- ,ogenous substances and. useful in the manufactureof containers for packing coffee, tea, tobacco 5 and various food products and like substances; particularly, those whichdeteriorate on exposure to the air, or which contain essential oils, or other odoriferous or flavoring materials which would be slowly dissipated on exposure to air.

It has been the custom to pack many materials of this class in paraflined paper, foils of tin, lead or aluminum, to overcome the deleterious effect of the air and the slowdissipation of essential flavoring material, either naturally occurring in the material or artificially added.

However, while these substances may preservethe contained materials, they are very weak and, accordingly, are rarely used alone but are supplev mented by other materials which are not impervious to air but which havethe advantage of greater strength, such as paper, paste-board, cardboard and other box boards, so as to protect the more frail material which possesses the property of being relatively impervious to air.

By coating a sized paper with a protelnogenous material such as casein, gelatine, albumin, etc., a'material which has much greater mechanical strength than foils or waxed paper, and also is impervious to air may be produced. By means i of this material it is possible to satisfactorily package many commodities in a manner which is cheaper and less bulky than methods now in e It is, therefore, an object of this invention to prepare a wrapping paper coated with a proteinogenous substance which will be tough, flexible, and substantially impervious to air and which may or may not be colored by the use of an organic dyestuflf.

' 40 It is a further object of this invention to prepare a coated paper useful for packaging various commodities, particularly those adversely affected by prolonged exposure to air, and also for other purposes.

The copending application of Edward M. Kratz and Herman Heckel entitled "Method and apparatus for making transparent sheet material, Serial No. 630,406, filed August 25, 1932, describes a coating composition which may advantageously be used in this preparation. The composition is prepared from two solutions which must be mixed just before application tothe per to be treated. One solution comprises a 10% solution of formaldehyde in water whilethe 65 other comprises casein dissolved in an aqueous alkali, or alkaline reacting substance, the 'pH value of the resulting solution being adjusted. This casein solution may suitably comprise about 13 to 14 per cent of casein and about 3.4 per cent glycerine, or other hygroscopic liquid, such as a 5 water soluble glycol, the balance being principally water. These two solutions should be mixed in the proportion of about 1 part of the formaldehyde solution to 22 parts of the casein solution v The mixture of these two solutions sets very 10 quickly, so that it is necessary to provide means whereby it may be utilized very quickly after its preparation. This is most advantageously accomplished by means of an apparatus described in the application Serial No. 630,406, referred to- 15 above. It comprises a proportioning pump which mixes the two solutions continuously and in small quantities and a coating device adapted to coat this material onto a forming belt before it has had time to set. In using this apparatus to pro- 20 duce coated paper, the forming belt is replaced by a suitable sized paper. After coating, the paper is dried and formed into rolls or formed into separate sheets as desired. It is preferable that a sized paper be used in order to prevent 25 the coating solution from soaking into the paper and producing a brittle product. The machine disclosed in my Reissue Patent. No. 17,854 may be modified in the manner indicated above and used for producing coated wrap- 30 ping paper. This machine is particularly well adapted for the application of gelatine'coatings. A strip of sized paper is run through the machine in place of the forming belt and the iestooning and drying operations may be employed in the 35 same manner as in the disclosure. of that patent.

Of course, it will be understood that any suitable drying process which permits the surface to dry out of contact with other objects may be used. A v 40 It is also possible to coat the paper with the casein solution only and then expose the coated sheet to 'the action of gaseous formaldehyde.

Any suitable proteinogenous coating may be used in this process. The coatings shown in my 45 Patents Nos. 1,847,656, 1,866,410, and 1,893,172 are suitable for this purpose.

The composition disclosed in U. S. Patent No.

' 1,893,172 comprises gelatin 9. sulfonated oil, and 0 a small amountof an acid.' Ordinarily, thepercentage of the sulfonated oil will lie between the limits of 5and 60 percent. A very satisfactory.

range is between 15 to 40 per cent, of the sulfonated oil. Preferably castor oil is used, which may contain between 4 and percent of the sulfonic acid radical (H803).

It is preferable to use a composition containing' about 25% of 8% sulfonated castor oil, of which 25% is water. Mypreferred proportions are as follows:

Parts by weight Gelatin 3 8% sulfonated oil 1 Water 12 Patent No. 1,866,410 discloses a composition similar to that of Patent No. 1,893,172, except that most of the sulfonated castor oil has been replaced by glycerine or a glycol such as ethylene glycol. It is desirable to have some sulfonated oil in it as the sulfonated oil serves to disperse the grease and fats found in the gelatin. A hardening or tanning agent, such as formaldehyde, may also be used to decrease the solubility of the product. It is sometimes necessary to add a small amount of a blue dyestuif to make the sheet appear white.

The Patent No. 1,847,656 discloses a gelatin composition comprising about 75% gelatin, of a sulfonated naphthenic acid and 10% of a light water white mineral oil. The addition of these substances to the gelatin prevents the development of any offensive odor or color in the coating with age.

A composition comprising gelatin, sulfonated castor oil and an aryl amine, such as diphenyl amine alpha-naphthylamine and betanaphthylamine may also be employed to produce my wrapping material. These aryl amines inhibit the tendency of the gelatin of the sheet to decompose. I have found the following ranges to be permissible in this composition:

Percent Gelatin 40 to 94 4% to 10% sulfonated castor oil 5 to 60 yl .5 to 5 Water in suitable proportion to dissolve the gelatin I prefer to keep the pH value of the composition between 5 and 6.

When it exceeds 6 by very much the composition becomes milky giving the finished product an unattractive appearance, and when it is less than 5 the product is seriously affected by humidity;

The composition described in my copending application; entitled Transparent sheet material, Serial No. 589,984, filed Jan. 30, 1932, may also be employed for this purpose. The composition there described comprises a mixture of gelatin, casein, and a plasticizer. Its advantage over gelatin alone is thata larger portion of plasticizer may be added without detrimental eflects.

An example of such a composition is as follows:

Parts by weight Casein p y 75 Gelatin 25 I Glycerine 15 to Bulfonated castor oil 10 to 12 Formaldehyde, 40% solution 2 When this composition is employed, it is desirable to chill it in the gelatin is used. It will beuhderstood that other emulsifiers and plasticizers may be employed in addition to, or in lieu of, those suggested in the above for- Sized paper is most suitable for the manufacture of this product because the sizing of the same manner 88 when pure paper makes it relatively impervious to water and consequently the interior of the paper will not become wetted by the coating solution in the time that elapses between its application and the drying operation. Such wetting is to be avoided for the purposes of my present invention as it weakens the paper to such an extent that it will not withstand the stresses applied to it at various points in the machine, and when dry does not possess a uniform appearance over its entire surface but looks cockled. The paper is also preferably used in the form of rolls so that the process will be practically continuous. It is unnecessary to treat both sides of the paper by this process in order to produce a water and moisture resisting sheet suitable for wrapping purposes. I

By the term sized", as applied to the paper which is to be used for coating, is meant a paper that has been sized with a good grade of rosin or animal glue sizing, or the equivalent. Such sized paper will withstand the penetration of water to the extent required for use in the preparation of my coated wrapping paper. A well sized bleached sulDhite paper for making a high grade of coated white paper is to be preferred, but well-sized kraft paper or other kinds may also be used.

It is to be understood that this invention differs from the usual method of tub sizing paper according to which unsized or only partially sized paper is passed through a bath of animal glue. In my process the starting material is finished paper, properly sized, and the coating is applied to a surface of the paper only by means of a fountain feed roll. Thereafter the coated paper is chilled and dried in a festoon drier or other suitable means which will'prevent anything coming in contact with the coated side of the paper to mar its finish or break .the continuity of the surface film.

The manner of treating the paper subsequently to the coating will depend upon the peculiarities of the coating material used, and whether it is desired to harden the coating or not. When the coating material is primarily gelatine, a chilling operation is desirable in order to cause the solution to set firmly before the drying operation. The solution may be exposed to the action of gaseous formaldehyde during this chilling step if desired. The may be employed advantageously at any time before drying and serves to harden the coating.

When a coating comprising principally casein is employed the chilling step should be replaced by a warming step. The formaldehyde or other hardener may then be incorporated into the casein mixture either Just before the coating operation, as described above, or the coating may be subjected to the action of gaseous formaldehyde before drying. The addition of the hardener to the solution before it is coated onto the paper is preferable, however, since a more complete incorporation of the hardener into the film is effected by this method.

Unlike a tub-sized paper, the coated paper of this invention has a surface film b y and the gelatine composition does not tially wet or penetrate the paper beca I already highly sized and therefore substantially water impervious.

It will be seen that this invention provides a paper coated with a homogeneous, uniform coating of a prot'elnogenous substance impervious to the atmosphere. Such a f the paper being coated paper is of great 76 my copending. application, entitled utility in packaging various commodities, and for numerous other uses, and in replacing more expensive and bulky methods 0! packing now in use to give a neat and wholesome appearance to the articles of which it forms a part.

This process makes a coated wrapping material which is very inexpensive and available in to produce containers for various commodities rapidly and automatically. v

s application is a continuation in part of Coated paper", Serial No. 509,888, filed January 19, 1931. I am aware that many changes may be made and numerous details of this invention may be varied through a wide range without departing tion of gelatine and'sulfonated castor oil, chilling and subsequently drying by festooning the coated web material to cause said gelatine composition to permanently adhere thereto without substantially wetting and penetrating the web material and without altering the natural, untreated finish of said gelatine composition.

2. The process of making air-impervious sheet material, which comprises coating a surface of a sized fibrous web material with an aqueous solution containing gelatine and a tanningagent, chilling and subsequently drying by festooning the coated web material to cause said gelatine composition to permanently adhere thereto without substantially wetting and penetrating the web material and without altering the natural, untreated finish of said gelatine composition.

3. The process of making air impervious sheet material, which comprises coating a surface of sized fibrous web material with an aqueous solution of an albuminous composition, chilling and subsequently drying by festooning the coated web wetting and penetrating the web material and producing a natural, untreated surface on said albuminous composition.

EDOUARD M. mm. 

